UNIT#04 LIQUIDS Flashcards
CHCl3 exist in a liquid state due to;
Dipole-Dipole Forces
The highest boiling point among the following is for:
Br2
(Intermolecular Force⬆ Vapour Pressure⬇ Boiling Point⬆)
➡has a stronger London Dispersion force due to molar mass
In NH3, dominant Van der Waal’s force among the following is:
Hydrogen Bonding
Liquids have no definite shape; it is because:
The molecules of the liquid are in constant motion by sliding over each other
Propanone is miscible in water due to:
➡Both are polar molecules
➡Hydrogen bonding between them
➡Dipole-Dipole attraction between them
Strong dipole-dipole forces among the liquid molecules are responsible for:
The very high heat of vaporization
Which one of the following arrangements usually represents the correct order of increasing interactions?
London Forces, Dipole-Dipole, Hydrogen Bonding
Which of the following has the strongest intermolecular forces of attraction
Iodine
(Molar mass⬆ Polarizability⬆ London Dispersion Force)
The forces which are present between the ions and water molecules are known as:
Ion dipole forces
Forces of attraction, which may be present between all kinds of atoms and molecules are:
London Dispersion forces
The attractive forces between the partially positive end of one molecule and the partial negative end of another molecule are called:
Dipole-Dipole forces
Liquid gets the shape of the container when it is poured into it. Which one of the following reasons justifies it
The liquid does not have a definite shape
The nature of bonding affects the properties like:
➡Solubility
➡Melting, Boiling Points and isomerism
➡Reaction Kinetics
The Vapour pressure of water is 4.579 torr and 9.209 torrs at 10° C, so the increase in vapour pressure from 0° C to 10° C is 4.630 torr. What will be the change in vapour pressure from 90° C to 100° C?
> 4.630 torr
Which of the following has the highest vapour pressure?
Iso-pentane➡has the weakest force of attraction
(V.P α 1/ Intermolecular Force)
The boiling point of water would be highest at:
Gawadar
Which one is false for evaporation:
Exothermic
(Evaporation is an endothermic process)
Vapour pressure of water at 100° C is:
760 mm Hg
The conversion of vapours back into other liquid states is called:
Condensation
Which one of the following has the highest volatility
Diethyl Ether
(L.D.F⬆ V.P⬇ Volatility⬆)
In order to mention the boiling point of water at 110° C, the external pressure should be:
Between 760 torr and 1200 torr
(Boiling point of liquid α External Pressure
The boiling point increases down the zero group element due to:
London Forces
If we provide a very high amount of heat to a liquid its boiling point will:
Remain constant
Evaporation is designated as a colling process because of the reason:
High energy molecules leave behind the low energy molecules and cause cooling
The Vapour pressure of a liquid depends upon the following:
Temperature and the inter-molecular forces
(➡V.P α Temperature
➡ V.P α 1/ Intermolecular Forces)
At 1atm pressure, liquid 1 has the boiling point less than liquid 2, what can we predict about both the liquids?
➡Liquid 1 has high vapour pressure than the liquid 2
➡Liquid 1 has a weak intermolecular force of attraction than the liquid 2
➡Liquid 1 is more volatile than the liquid 2
The distillation of a solution under reduced pressure is called:
Vacuum Distillation
A pressure cooker reduces cooking time because:
The boiling point of water rises
Molar heat of vaporization of water is:
➡40.6 kJ/mol
The rate of evaporation of a liquid depends upon:
➡Surface area of liquid
➡Temperature
➡Intermolecular Forces
Which one of the following would cause severe burning
Steam at 100° C
The boiling point of a liquid is the temperature at which
The vapour pressure of the liquid is equal to the atmospheric pressure
The strength of hydrogen bonding is:
20 times less than a covalent bond
When ammonia is dissolved in water, a number of hydrogen bonds formed with ammonia
1
(as there is one lone pair)
Lower alcohols are soluble in water because:
Intermolecular Hydrogen bonding
The strongest H-bond is:
F—H
When two ice cubes are passed over each other, they unite to form one cube. This is due to:
Hydrogen Bond Formation
Which of the following can form hydrogen bonding among its molecules more prominently
CH3OH
Hydrogen bonding is involved in:
➡Solubility
➡Cleasnsing action of detergents
➡Biological molecules
When water freezes at 0° C its density decreases due to:
Empty space present in the structure of ice
The correct order of boiling point of the given liquids is:
H2O>HF>NH3>HCl
At 1489 mmHg, water will boil at:
120° C
Ice is less dense than water at:
0° C
In a crystal lattice of ice, each O-atom of the water molecule is attached to:
Four H-atom
What is the reason that the ice at 0° C occupies more volume than water:
Empty spaces
Water has maximum density at:
4° C
DNA molecule is double-stranded, in which two chains of DNA are twisted around each other by:
Hydrogen Bond
Which of the following substances exhibits hydrogen bonding?
NH3
In the ‘H-F’ bond electronegativity difference is 2.0. What is the type of this bond?
Polar covalent bond
The boiling point of water is higher than petrol because intermolecular forces in water are:
Stronger than petrol
Metallic conduction involves the relatively free movement of their _____ throughout the metallic lattice:
Electrons
Which type of force is present in gasoline?
London Dispersion forces
Which one of the following hydrogen bonds is stronger than the other?
F-H——F-H
An intermolecular force of attraction X is relatively stronger than the other intermolecular forces, it stabilizes α-helix and β-pleated sheets of proteins. The double helical structure of DNA is also stabilized by this force of attraction. Identify X
Hydrogen Bonding
At higher altitudes, the boiling point of water is less than 100° C, this is because of:
Lower atmospheric pressure
Steam causes more severe burns than boiling water. It is due to:
High Latent Heat of vaporization
According to Watson and Crick’s model of DNA, the DNA molecule consists of the double helix. What type of forces is responsible to keep two strands of DNA together?
Hydrogen Bonding
CO2 and SO2 both are tri-atomic molecules but the heat of vaporization of SO2 is greater than that of CO2 due to:
SO2 is polar and CO2 is non-polar
Which of the following has the lowest vapour pressure at 20° C?
Water
Which of the following is not a molecular solid?
Bromine
The distillation which is carried out under reduced pressure is called as
Vaccum Distillation
In which of the following water evaporate earlier
Sauce pan
Conversion of water into steam is a
Spontaneous reaction
On which factors the vapour pressure of a substance does not depend
Surface Area
How many times of covalent bond is stronger than hydrogen bond
20 times
Separation of components of liquid on the basis of their boiling point called as
Fractional Distillation
Which instrument is used to measure the vapour pressure of a liquid
Manometer
Which of the following has highest vapour pressure
Diethyl ether
When heat provided to a liquid it causes it to
Expand
Which of the following intermolecular forces are present between Octane molecule
London Dispersion froces
Which of the following forces ability to form strong bonds
H-bond
At zero degree centigrade what is the physical state of water
Both ice and liquid
Steam cause more advanced than boiling water because it has:
Latent heat of vaporization
Hydrogen bonding is involved in
➡Biological molecules
➡Cleansing action of soap
➡Solubility
In vacuum distillation the boiling point of glycerine is reduced to
210° C
Hydrogen bonding is stronger than
➡Dipole Dipole Forces
➡London Forces
➡Debye Forces
While calculating vapour pressure of a liquid in manometer the column of mercury facing the vapours of a liquid is ___ due to pressure on surface of liquids in flask:
Depressed
The measurement of the extent to which electron cloud is distorted is termed as
Polarizability
Molecules of liquids are in a constant state of motion it causes
➡Diffusion
➡Evaporation
In the formation of HF,_____ donates the measure of its electron among hydrogen atom of chlorine atom
Boiling Point
HF has high boiling point than HCl is:
Hydrogen Bonding
The molecules of ___ have dipole-dipole interaction
Ammonia
Hydrogen bonding is maximum in
Water
When two ice cubes are passed over Each Other they Unite to form 1 cube. This is due to
Hydrogen bond formation
Rate of evaporation of a liquid does not depend on
External pressure
Which one of the following would cause severe burning
Steam at 101°C
Which of the following in liquid has lowest boiling point
CH3OH
In which of the following of the pairs, debye forces exist
Argon and water💦
Kerosene oil is liquid at room temperature due to
London dispersion forces
The heat of vaporization of H2O, C2H5OH and CS2 are 40.6KJ/mol, 38.6 KJ/mol,28.6 KJ/mol. The order of decreasing intermolecular forces in these liquids is:
H2O > C2H5OH > CS2
A substance that is soluble in water due to dipole-induced dipole force:
Kr
(Krypton is non-polar
Naphthalene is soluble in carbon tetrachloride due to the force:
London Forces
The polarizabilities of electrons mostly increase down the group due to the;
Increase in the number of shell
London forces are more significant in:
Non-polar molecules
Which of the following intermolecular forces may be present in molecular solids:
➡Dipole-Dipole Forces
➡Van der Waal’s Forces
➡Hydrogen Bonding
Which of the following highest boiling point
n-hexane
(Boiling Point ∝ Polarizability ∝ Molecular Size)
Molar heat of vaporization is the highest for:
Iodine
(Size of molecules ∝ Polarizability)
Which pair shows Debye forces:
HCl and Ar
(➡HCl is a polar molecule
➡Ar is a non-polar)
Value of gas constant “R” is ____ if unit is atm dm3 mol-1 K-1
0.0821
Which gas show marked deviation rom ideal behaviour?
CO2
Which statement about evaporation is incorrect?
It is exothermic process
Vapour pressure of a liquid depends upon one of the following factors
Inter molecular forces
Vapour pressure of liquid is measured when liquid and the vapours are in equilibirum it means that:
Rate of evaporation equal to the rate of condensation
Vapour pressure of water at 100°C is:
760 mmHg
The boiling point of water is maximum when external pressure is:
1489 torr
Water can boil at;
➡25°C
➡100°C
➡120°C
NH3 shows maximum boiling point among the hydrides of group VA element due to;
Enhanced electronegative character of nitrogen
Moving from 4°C to 0°C, the density of H2O:
Decreases
The H2O cannot make h-bonding with:
CH4
Water has maximum density at:
4°C
London dispersion forces are present in;
➡I2
➡H2
➡He
The rate of vapourization of gasoline is faster than water due to:
Weak London Forces
Which one of the following is a solid with lowest melting point:
I2
The low acidic strength of HF molecule as compared to HCl is due to:
Hydrogen Bonding
Which one of the following arrangements represents the correct order of increasing interactions:
London Forces, Dipole-Dipole, Hydrogen Bonding
The inter-molecular attractive forces vary in the order;
Ether < Alcohol < Water
Heat of vaporization is minimum for;
HCl
If we provide very large amount of heat to a liquid, its vapor pressure at its boiling point:
Remains the same
The vapor pressure of water at 0°C is:
4.8 torr
The boiling point of H2O is greater than that of C2H5OH due to;
Numebr of H-bonds are greater in H2O than in C2H5OH
A substance with maximum vapor pressure at 25°C
Diethyl ether
During which process the particles come so close to each other that the empty spaces between them are minimum:
Condensation
Steam causes more severe burn than the boiling water because it possesses:
Latent heat of vaporization
At top of Everest water boils at 69°C the external pressure is:
323 torr
The boiling point of water would be highest at:
Karachi
Which gas is most soluble in water:
NH3
(Compounds making strong hydrogen bond)
Which one among the following does not have the hydrogen bond?
Liquid HCl
H2O has higher boiling point than H2S because;
Of intermolecular hydrogen bonding in liquid H2O
DNA molecule is double stranded, in which two chains of DNA are twisted around each other by:
Hydrogen bonds
Density of liquid water ___ if temperature decreases from 25°C to 0°C
First increases and then decreases
Forces of attractions in liquids are:
➡Stronger than gases
➡Weaker than solids
Rather than gases in liquid contain ____
Fix volume
If we increase or decrease the amount of heat in a liquid, its boiling point will;
Remains constant
Which is the correct order of boiling points?
H2O > HF > NH3 > CH4
Evaporation of water depends upon the following;
➡Sruface area an intermolecular forces
➡Speed of the air above the liquid surface
➡Humidity of air
110°C boiling point of water corresponds to the external pressure
Between 760 to 1200 torr
The boiling point of a compound is mostly raised by;
Intermolecular Hydrogen bonding
Which has a greater enthalpy of vapourizaton
I2
Identity incorrect statement about evaporation;
➡Exothermic✅
➡Continuous❌
➡Cooling❌
➡Surface Phenomenon ❌
Maximum vapour pressure is shown by:
➡50 cm^3 ethanol
➡1 dm^3 ethanol
Evaporation occurs at:
All temperature
Which one is the most accurate method for the measurement of vapour pressure
Manometric Method
Vapour pressure of methanol at 40°C is less than;
Ether
Ionic crystals are characterized by:
Solubility in Polar solvents
NaCl crystal is;
Cubic
Which element exists as a discrete small molecule in the solid state;
Iodine
Ice floats on the liquid water because:
Water freezes at 0°C and is less dense than liquid water
The density of an unknown gas ‘X’ is 1.98 g/dm^3 at STP. Unknown gas is:
CO2
Which one of the following contains maximum hydrogen bonding?
H2O
Ammonia shows the maximum boiling point because fo;
Enhanced electronegativity character of nitrogen
The boiling point of H2O is 100°C while that of C2H5OH is 78.37°C. The reason is that:
The number of hydrogen bonds per H2O molecule is greater than C2H5Oh
Which of the following in the liquid state has the lowest state boiling point?
CH3OH
In which of the following pairs, do Debye forces exist:
➡Argon
➡Water
Kerosene oil is liquid at room temperature due to:
London Dispersion forces
Which of the following can form hydrogen bonding among its molecules more prominently
CH3OH
Identify the incorrect statement about evaporation:
➡Continuous❌
➡Cooling❌
➡Exothermic✅
➡Surface❌
Exceptionally low acidic strength of HF is due to;
Strong hydrogen Bonding
In which of the following pairs, do Debye forces exist:
➡Argon
➡Water
A pressure cooker reduces cooking time because;
The boiling point of water rises
Hydrogen bonding is maximum in:
Water
Molar heat of vaporization of water is;
40.6 kJ/mol
The strongest H-bond is;
F—H
Maximum vapour pressure is shown by:
➡1 dm^3 ethanol
➡50 cm^3 ethanol
The Vapour pressure of a liquid depends upon the following;
Temperature and the inter-molecular forces
At 1 atm pressure, liquid 1 has the boiling point less than liquid 2, what can we predict about both liquids
➡Liquid 1 has high vapour pressure than the liquid 2
➡Liquid 1 has a weak intermolecular force of attraction than the liquid 2
➡Liquid 1 is more volatile than the liquid 2
The strength of hydrogen bonding is:
20 times less than a covalent bond
110°C boiling point o water corresponds to the external pressure.
Between 760 torr to 1200 torr
Lower alcohols are soluble in water because;
Intermolecular Hydrogen bonding
Ammonia shows the maximum boiling point because o;
Enhanced electronegativity character of nitrogen
Ice floats on the liquid water because:
Water freezes at 0°C and is less dense than liquid water
Hydrogen bonding is extensively present in protein which forms the spiral. The hydrogen bond being produced is between;
➡Oxygen
➡Hydrogen
Ice occupies more space than liquid water:
9%
The boiling point of water is 100°C while that of C2H5Oh is 78.5°C. The reason is that :
The number of hydrogen bonds per H2O molecule is greater than C2H5OH
The distillation of a solution under reduced pressure is called:
Vaccum Distillation
Which liquid has the lowest vapour pressure
H2O
The boiling point of a compound is mostly raised by:
Intermolecular Hydrogen Bonding
Propanone is miscible in water due to;
➡Both are polar molecules
➡Dipole-Dipole attraction between them
➡Hydrgoen bonding between them
Which has a greater enthalpy of vaporization;
I2
